Audiobus: Use your music apps together.

What is Audiobus? — Audiobus is
an award-winning music app for iPhone and iPad which lets you use
your other music apps together. Chain effects on your favourite
synth, run the output of apps or Audio Units into an app like
GarageBand or Loopy, or select a different audio interface output
for each app. Route MIDI between apps — drive a
synth from a MIDI sequencer, or add an arpeggiator to your MIDI
keyboard — or sync with your external MIDI gear.
And control your entire setup from a MIDI controller.

Comments

Yes! I'm getting the same thing and concerned about it. I was getting it inside of Audiobus 3 with a few synths loaded and the CPU looked like it was only at 53% at the time I noticed it. Was going to post out to try and see if anyone has a fix for it. I was wondering if it could be some system setting for audio buffer size or something.

My non-technical summary of the thread @richardyot mentions above is that this is a massive problem with how CoreAudio on iOS is managed on the new 2018 iPad Pro (both 11" and 12.9"). Its got something to do with the low-power (instead of high-power) CPU threads being tasked to manage synth apps and getting all mucked up.

The general concensus is:

Apple's CoreAudio team knows about it, has fixed it, and will implement an update

Music app developers have no way to work around or avoid it. It has to be (and is being) fixed by an iOS update

we musicians/ users can do nothing to fix it but wait or return our shiny new iPads and get a dusty old 2015 12.9"

@gkillmaster said:
I'm not sure if its related to the cpu spiking issue or nor...

yep, same thing. CPU spikes cause crackles. When a real-time audio process doesn't have the CPU power to do its thing in real-time then crackles happen. I think in AUM the spikes register on the CPU meter, and maybe in Audiobus the CPU meter doesn't always register quick spikes. But either way, we notice their effect on the audio: massive crackles.

@gkillmaster said:
I'm not sure if its related to the cpu spiking issue or nor...

yep, same thing. CPU spikes cause crackles. When a real-time audio process doesn't have the CPU power to do its thing in real-time then crackles happen. I think in AUM the spikes register on the CPU meter, and maybe in Audiobus the CPU meter doesn't always register quick spikes. But either way, we notice their effect on the audio: massive crackles.

I really hope it's fixable. For me, the whole reason to get an iPad is for music making.

It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

@gkillmaster said:
I'm not sure if its related to the cpu spiking issue or nor...

yep, same thing. CPU spikes cause crackles. When a real-time audio process doesn't have the CPU power to do its thing in real-time then crackles happen. I think in AUM the spikes register on the CPU meter, and maybe in Audiobus the CPU meter doesn't always register quick spikes. But either way, we notice their effect on the audio: massive crackles.

I really hope it's fixable. For me, the whole reason to get an iPad is for music making.

THIS! This is true for all my computing devices (beside my smartphone).

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

This must be why Apple missed it. There aren't giving it enough stress testing for audio, just for graphics. Hopefully this development has changed their ways.

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

This must be why Apple missed it. There aren't giving it enough stress testing for audio, just for graphics. Hopefully this development has changed their ways.

I have had it just playing a pad patch from Bryce's pack for Zeeon and some of the factory patches in Model D. So definitely not just a music app stress issue but like mentioned above, something to do with the CoreAudio bug. When it seems to manifest is random for some people (probably based on background apps/activity)

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

This must be why Apple missed it. There aren't giving it enough stress testing for audio, just for graphics. Hopefully this development has changed their ways.

Probably worst... they are giving all the power for graphics wrecking audio... but you know, iPad are wacom replacement more than audio studio centerpiece...

@brambos These are still my needs?
Apple needs to fix its strategy on iOS before call anything Pro...

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

This must be why Apple missed it. There aren't giving it enough stress testing for audio, just for graphics. Hopefully this development has changed their ways.

Probably worst... they are giving all the power for graphics wrecking audio... but you know, iPad are wacom replacement more than audio studio centerpiece...

@brambos These are still my needs?
Apple needs to fix its strategy on iOS before call anything Pro...

Not sure why I'm being summoned in this response? Instead of complaining about everything Apple and iOS I actually invest time in trying to build something nice on the platform. If there's nothing good about the platform, may I suggest moving on and putting your energy into something else?

@brambos said:
Not sure why I'm being summoned in this response? Instead of complaining about everything Apple and iOS I actually invest time in trying to build something nice on the platform. If there's nothing good about the platform, may I suggest moving on and putting your energy into something else?

@Tarekith said:
It's not totally unusable. I haven't experienced the crackles once on my 11" Pro using some pretty big Groovebox and KEW sessions or with normal daily use. Even using Model 15 on its own has been fine for me. Sounds like I don't run as many big gun apps at the same time as a lot of people though..

Agreed, its not terrible... just worse than what you would expect from something advertised as "better than 70% of laptops."

I didn't see any problems until I set up 4 instances of Model D inside AUM on the 11" 256GB. The setup process was crackle city. But once it was all up and going, CPU stayed at about 53% and solid, no problems.

This must be why Apple missed it. There aren't giving it enough stress testing for audio, just for graphics. Hopefully this development has changed their ways.

Probably worst... they are giving all the power for graphics wrecking audio... but you know, iPad are wacom replacement more than audio studio centerpiece...

@brambos These are still my needs?
Apple needs to fix its strategy on iOS before call anything Pro...

Not sure why I'm being summoned in this response? Instead of complaining about everything Apple and iOS I actually invest time in trying to build something nice on the platform. If there's nothing good about the platform, may I suggest moving on and putting your energy into something else?

You are summoned due in the last discussion we had you said (like this one) that was/is my problem. Well I stated clearly my feelings about the platform and brand but also my arguments about why not is just a personal issue. Obviously I’m putting my energy into something else (I participate less and less) but since in the other topic other users started to say similar things to mine I wanted to invite you to participate in this and bring some info from the dev side. You are a well recognized developer (‘cause you deserve it) and I want to be proved wrong (in fact I hope it since I still love the community and the platform, it’s Apple who droves me a bit crazy) so can you talk us about how latest iOS iterations manages GUI vs CoreAudio? As someone stated above “Apple is aware of this and fixing it” I will love to know your opinion on that and how it fits in the whole iOS is a professional platform we had discussing.

The summoning call just to put you in context why I done it. Not an issue with you in the end... I love to discuss with passionate people like me. Very often from those discussion everybody learn and say sorry mate isn’t so hard.

I also experience crackling on my iPad Pro 11". It might be a sample rate mismatch problem, when using the built-in speakers it's not possible to set AUM to 44.1kHz for example, it's running on 48kHz by default. As soon as I connect an audio interface it becomes possible to switch to 44.1kHz and the crackling seems to stop.

Mr. Bram and other knowledgeable contributors (high-fives all around) have already helped sort this out.

Go to the other thread mentioned above if you want to try to wrap your hear around it. I am content to see that it seems like those who actually understand this stuff got the answers they wanted from Apple and it is just a matter of when we'll see the attempted fix in an iOS update.

@balph said:
I also experience crackling on my iPad Pro 11". It might be a sample rate mismatch problem, when using the built-in speakers it's not possible to set AUM to 44.1kHz for example, it's running on 48kHz by default. As soon as I connect an audio interface it becomes possible to switch to 44.1kHz and the crackling seems to stop.

Go to the other thread mentioned above if you want to try to wrap your hear around it. I am content to see that it seems like those who actually understand this stuff got the answers they wanted from Apple and it is just a matter of when we'll see the attempted fix in an iOS update.

@balph said:
I also experience crackling on my iPad Pro 11". It might be a sample rate mismatch problem, when using the built-in speakers it's not possible to set AUM to 44.1kHz for example, it's running on 48kHz by default. As soon as I connect an audio interface it becomes possible to switch to 44.1kHz and the crackling seems to stop.

The fixed sample rate is normal. Many iOS device models are locked to 48kHz for the internal speakers. AUM uses the actual hardware sample rate to avoid sample rate conversion.

@balph said:
I also experience crackling on my iPad Pro 11". It might be a sample rate mismatch problem, when using the built-in speakers it's not possible to set AUM to 44.1kHz for example, it's running on 48kHz by default. As soon as I connect an audio interface it becomes possible to switch to 44.1kHz and the crackling seems to stop.

The fixed sample rate is normal. Many iOS device models are locked to 48kHz for the internal speakers. AUM uses the actual hardware sample rate to avoid sample rate conversion.

Using the native sample-rate of the hardware is a good thing I suppose?!

Since the sample-rate can vary between different hardware I does make me question why so many apps assume a 'fixed' sample rate instead of 'adapting' to the currently active sample-rate?

I do get that some apps are optimised (for example pre-calculated tables) for a certain sample-rate for maximum performance but that comes at a cost of compatibility when the target sample-rate changes.

I do get that for example when using Cubasis there may be a need to work with non-native sample-rates and that can also present a challenge and slow things down if too much sample-rate conversion needs to be done.

It could be even argued that the crackles when doing the sample-rate conversions could be Core AudioBugs but that's another matter...

I am pretty sure it's an iOS issue. So far, it seems to me it has to do with sample rates being wrongly assigned, especially for Auv3s. I ran a few tests today and Mood runs properly with headphones solo or Auv3 but can't damn run Auv3 on the ipad speakers without crackling like crazy. They have the most advanced CPU on any mobile device on earth but can't manage to pull enough brains to get iOS not to suck badly for music production. Tim Cook doesn't like music I guess.

Buying an iPad Pro for 2 or 3 years, loosing 3 months or more for earlier audio glitches fixing, loosing another 2 or 3 months for apps fixing (if ever for some of them?) every annual iOS big update... this is an expensive platform, and is unfortunately a major issue for any professional use, especially for live situations. Loving making music with iOS and its wonderful apps has nothing to do with this. When you really love/need the platform, only choice is to always keep a not updated older backup device. Again, expensive. Asking for reliability or just something that works is pretty legitimate IMO.

Yeah, asking that it keeps at least the quality standards between each iteration is not too much to ask when we are talking about a machine over 1000$. Don't they have testers internally before releasing their products?

That's good to hear. I wonder if the fix will improve any performance for Pro 12.9 2017 as well? It doesn't mention in those notes.
I'm not having any major issues but wouldn't say no to performance improvements

@Carnbot said:
That's good to hear. I wonder if the fix will improve any performance for Pro 12.9 2017 as well? It doesn't mention in those notes.
I'm not having any major issues but wouldn't say no to performance improvements